1. Field of Invention
The present invention mainly relates to electromagnetic driving devices used on vehicles, and particularly to an electromagnetic fan clutch and an air pump device, and methods for manufacturing and controlling the same.
2. Description of Related Arts
At present, an electromagnetic fan clutch used on an automobile controls the rotation speed of a fan according to the change of water temperature of an engine, so that the engine of the automobile is remained in the optimal state during the operation process. Specifically, by controlling the energization or de-energization of a coil on an electromagnetic iron core, a suction disc on a magnet fixing disc or a fan fixing disc is controlled to be engaged with or disengaged from a driving disc, thereby controlling the rotation speed of a fan on the fan fixing disc, so as to achieve the effect of cooling the engine by the fan at a proper rotation speed.
As shown in FIG. 1, an existing electromagnetic fan clutch (taking a three-speed electromagnetic fan clutch as an example) comprises a main shaft 1′, a driving disc 2′, an electromagnetic iron core 3′, an outer coil 4a′, an inner coil 4b′, a fan fixing disc 9′, a magnet fixing disc 10′, a small spring sheet 12′, a small suction disc 13′, a large spring sheet 34′, a large suction disc 35′ and a safety plate 36′, wherein the driving disc 2′ made of magnetic conductive material is fixedly mounted on the main shaft 1′ via a half round key 19′. Several sets of magnetic insulation grooves 23′ are provided on a side of the driving disc 2′. The electromagnetic iron core 3′ is provided inside an inner cavity of the driving disc 2′. The electromagnetic iron core 3′ is mounted on the main shaft 1′ via a bearing 5′, and provided therein with inner and outer coil inlay slots, respectively. The directions of magnetic conductive opening of the inner and outer coil inlay slots are both the same as the axial direction of the main shaft 1′ and directed to the side of the driving disc 2′. The inner and outer coil inlay slots are provided with an inner coil 4b′ and an outer coil 4a′ in a flat winding manner, respectively. The fan fixing disc 9′ and the magnet fixing disc 10′ are mounted on the main shaft 1′ via bearings 8′ and 11′, respectively, wherein several fixing holes for inlaying soft magnets 15′ are uniformly distributed on an end face of the magnet fixing disc 10′ in the fan fixing disc 9′ along the circumference. Permanent magnets 14′ are sucked on the soft magnets 15′. Soft magnets 16′ are inlaid on an end face of the fan fixing disc 9′ corresponding to the permanent magnets 14′. The small suction disc 13′ is supported and connected to an annular end face of the magnet fixing disc 10′ opposite to the inner coil 4b′ via the small spring sheet 12′. The large suction disc 35′ is supported and connected to an annular end face of the fan fixing disc 9′ opposite to the outer coil 4a′ via the large spring sheet 34′. Both the small suction disc 13′ and the large suction disc 35′ are close to the side of the driving disc 2′, and have a space with the corresponding end face of the driving disc 2′. The safety plate 36′ is fixedly connected to the end face outside the circumference of the fan fixing disc 9′, and provided thereon with a locking hole. A mating hole is provided at a position outside the circumference of the driving disc 2′ corresponding to the locking hole.
The specific working process of the three-speed electromagnetic fan clutch is as follows: when the temperature of an engine does not reach a low temperature set value (for example, 82° C.) of the three-speed electromagnetic fan clutch, both the inner and outer coils 4b′ and 4a′ in the electromagnetic iron core 3′ are not energized, and the driving disc 2′ will neither suck the small suction disc 13′ on the magnet fixing disc 10′ nor suck the large suction disc 35′ on the fan fixing disc 9′. The fan fixing disc 9′ slides and rotates freely via the bearing 8′, and the magnet fixing disc 10′ slides and rotates freely via the bearing 11′. When the temperature of the engine reaches the low temperature set value (82° C.) and is less than a high temperature set value (for example, 88° C.), the inner coil 4b′ is energized, and as the magnetic effect of the electromagnetic iron core 3′ allows the driving disc 2′ to suck the small suction disc 13′, the small suction disc 13′ and the driving disc 2′ rotate synchronously. The small suction disc 13′ drives the magnet fixing disc 10′ to rotate at a full speed via the small spring sheet 12′. The soft magnets 16′ inlaid in the fan fixing disc 9′ perform relative rotation in a magnet field formed by the permanent magnets 14′ and the soft magnets 15′ in the magnet fixing disc 10′ so as to cut magnetic lines of force and generate eddy current by themselves. The eddy current generates a new magnetic field, so that the flexible connection and middle-speed rotation of the fan fixing disc 9′ and the magnet fixing disc 10′ are realized under the action of the magnetic field, and the effects of primary heat dissipation and cooling are achieved. When the temperature of the engine rises to the high temperature set value (88° C.), the outer coil 4b′ is energized to generate suction force, so as to suck the large suction disc 35′ onto the driving disc 2′. The large suction disc 35′ and the driving disc 2′ rotate synchronously, and the large suction disc 35′ drives the fan fixing disc 9′ to rotate at a full speed via the large spring sheet 34′, thereby achieving the forceful cooling effect.
However, during the running process of a vehicle, if a power supply system of the electromagnetic fan clutch suddenly malfunctions or is suddenly de-energized, the inner and outer coils 4b′ and 4a′ fail to work, the rotation speed of the fan blade on the fan fixing disc 9′ cannot be controlled to cool the engine by controlling the energization and de-energization of the inner and outer coils 4b′ and 4a′. Certainly, the original design structure of the electromagnetic fan clutch is usually provided with a safety plate 36′ fitted with an emergency locking bolt carried on the vehicle, and a corresponding locking hole and mating hole. Thus, the driver may park as soon as possible after the power supply system of the electromagnetic fan clutch malfunctions, and then insert the emergency locking bolt into the locking hole on the safety plate 36′ and the mating hole on the driving disc 2′, so that the fan fixing disc 9′ and the driving disc 2′ synchronously rotate and the fan rotates at a full speed to cool the engine. If the driver knows that the power supply system malfunctions during driving the vehicle, the driver may park and then fix the fan fixing disc 9′ and the driving disc 2′ by using the emergency locking bolt, so that the fan rotates at a full speed for cooling. However, it often cannot be assured that the driver can know the malfunction condition at the first time, so the driver cannot park timely to use the emergency locking bolt, and it is relatively troublesome to park to mount the emergency locking bolt. Even if the driver can know the malfunction of the power supply system at the first time, the actual running road condition of the vehicle is complicated and varied. Therefore, in certain particular running environments, the driver cannot park or cannot immediately park to employ bolt locking measures, so that it is possible to cause high-temperature damage and even scrapping of the engine, and even traffic accidents are caused in serious cases. So, the consequences would be unimaginable. In addition, as shown in FIG. 1, when the water temperature of the engine rises to the high temperature set value (88° C.), in order to meet the requirements that, after the outer coil 4a′ is energized, the electromagnetic iron core 3′ can have magnetism large enough to suck the large suction disc 35′ fixedly connected to the fan fixing disc 9′ onto the driving disc 2′ and drive the fan fixing disc 9′ and the driving disc 2′ to rotate at the same speed, and the engine is required to provide continuous power to the outer coil 4a′. Thus, larger electric energy is consumed, the power loss of the engine is increased, the engine originally in a high temperature state is further operated in an overloaded state, and the service life of the engine is reduced.
At present, during the running process of a vehicle, air pump devices for vehicle braking systems control air pumps to work by energizing or de-energizing electromagnetic clutches. When the pressure within an air pump is less than a pressure value (for example, 6-8 kg) required by the operation of a braking system, a power supply system of the electromagnetic clutch energizes, and a component for driving a spindle of the air pump to rotate is connected to a rotating belt wheel (the belt wheel is rotated driven by an engine) through the suction force of an electromagnetic iron core, so that the spindle of the air pump and the belt wheel rotate synchronously, thereby achieving the purpose of making the air pump in a working state. When the pressure within the air pump reaches or exceeds the pressure value (for example, 6-8 kg) required by the operation of the braking system, the power supply system of the electromagnetic clutch is de-energized, the spindle of the air pump is disengaged from the belt wheel, and the air pump stops working. However, if the power supply system of the electromagnetic clutch malfunctions, a sudden power cut occurs or the electromagnetic clutch has other failures during the running process of the vehicle, the electromagnetic clutch cannot control the air pump to work in this case, so that the function of the air pump is influenced, the braking system cannot work normally, then it is possible to further result in a series of serious consequences, and a safety guarantee cannot be provided for the driver. Certainly, safety structures for preventing an air pump control system from failure is also mounted on a part of existing vehicles, but it is required to stop the vehicle in the use of these safety structures, and the failure resistant structures are started manually, so there are certain limitations.